The present invention relates generally to endoscopic spinal surgery, microdiscectomy, and to the identification of neural tissue during these procedures. More particularly, the present invention is directed to a switching device used to alternatively allow bipolar surgical dissection or produce nerve stimulation using a single surgical instrument through the working channel of the endoscope without the need to introduce or exchange additional instruments.
Minimally invasive spinal surgery has greatly increased the convenience and safety of treatment of common painful spinal conditions. Endoscopic microdiscectomy with or without foraminotomy is one such approach to the treatment of herniated disc and spinal stenosis utilizing small tubular retractor instrument systems and high resolution digital video endoscopes to access and treat soft tissue and bony pathology within the spinal canal with minimal tissue trauma associated with the procedure.
Current generation spinal endoscopes are equipped with “working channels” that allow the placement of operating instruments within the diameter of the endoscope itself, thus limiting the size of the entire surgical access window to a single portal, typically 7-10 mm in diameter. The ability to place all operating instruments through the working channel further complements the essential goals of minimal tissue trauma for operating efficiency, safety, reduced operating time, and fewer surgical complications.
In endoscopic spinal surgery, rapid and reliable identification of neural tissue is essential to safe practice. The clinical use of sensory and motor nerve stimulation has become a mainstay of current open spinal surgery and endoscopic surgical practice by a variety of methods. Existing methods of neural monitoring during spine surgery such as elaborate EMG and SSEP devices require that nerve injury be imminent or actual as a condition of detection. Direct electrical stimulation of a suspected neural structure, however, is a proven method of prospective neural identification without threatened or actual injury to the nerve. Thus, the ability to provide direct electrical stimulation to suspected neural structure while performing minimally invasive endoscopic surgery would be highly beneficial and especially beneficial during physician training or proctoring to help shorten the learning curve and decrease the potential for patient injury while developing experience with endoscopic techniques. In addition, when performing procedures on awake or lightly sedated verbally responsive patients, symptoms referable to a specific neural territory may be confirmed during surgery to further confirm surgical treatment efficacy.
Accordingly, there is a need for a device and method for providing direct atraumatic identification of neural tissue by electrical stimulation through the working channel of the spinal endoscope.